Re: svn commit: r231383 - in head: lib/libutil usr.sbin/vipw
On Friday, February 10, 2012 8:40:32 am Ed Schouten wrote: Author: ed Date: Fri Feb 10 13:40:32 2012 New Revision: 231383 URL: http://svn.freebsd.org/changeset/base/231383 Log: Detect file modification properly by using tv_nsec. POSIX 2008 standardizes st_mtim, meaning we can simply use nanosecond precision to detect file modification. MFC after: 2 weeks Eh, the BUG is still worth mentioning. By default FreeBSD only uses second granularity for VFS timestamps, so two updates within a single second is still racey. You can keep the code change, but I would revert the manual page change to put the BUG back as your change didn't remove it. -- John Baldwin ___ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to svn-src-head-unsubscr...@freebsd.org
Re: svn commit: r231383 - in head: lib/libutil usr.sbin/vipw
* John Baldwin j...@freebsd.org, 20120213 17:26: Eh, the BUG is still worth mentioning. By default FreeBSD only uses second granularity for VFS timestamps, so two updates within a single second is still racey. You can keep the code change, but I would revert the manual page change to put the BUG back as your change didn't remove it. I'll re-add it tomorrow. I do think I will extend the message a bit, stating that this is only a problem if your file system doesn't do fine-grained timestamps. -- Ed Schouten e...@80386.nl WWW: http://80386.nl/ pgpFLerv0Ihwi.pgp Description: PGP signature
Re: svn commit: r231383 - in head: lib/libutil usr.sbin/vipw
On 10 February 2012 17:40, Ed Schouten e...@freebsd.org wrote: Author: ed Date: Fri Feb 10 13:40:32 2012 New Revision: 231383 URL: http://svn.freebsd.org/changeset/base/231383 Log: Detect file modification properly by using tv_nsec. POSIX 2008 standardizes st_mtim, meaning we can simply use nanosecond precision to detect file modification. I am not sure we can use subsecond precision there with currently set sysctl vfs.timestamp_precision=0. -- wbr, pluknet ___ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to svn-src-head-unsubscr...@freebsd.org
Re: svn commit: r231383 - in head: lib/libutil usr.sbin/vipw
On Fri, 10 Feb 2012, Sergey Kandaurov wrote: On 10 February 2012 17:40, Ed Schouten e...@freebsd.org wrote: Log: ?Detect file modification properly by using tv_nsec. ?POSIX 2008 standardizes st_mtim, meaning we can simply use nanosecond ?precision to detect file modification. I am not sure we can use subsecond precision there with currently set sysctl vfs.timestamp_precision=0. Also, not all file systems support even seconds precision. So the deleted BUGS section applies irrespective of vfs.timestamp_precision, except it doesn't describe the full extent of the problem. Sleeping for just 1 second is not enough if the timestamp precision is large. The BUGS section also applies respective of vfs.timestamp_precision, when the user uses the supported setting vfs.timestamp_precision=0. Of course, important databases that need POSIX semantics shouldn't be put on file systems without POSIX times, but you need a BUGS section somewhere to tell you not to do that. Bruce___ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to svn-src-head-unsubscr...@freebsd.org
